Add meal plan feature with cross-device sync and automatic stale data cleanup

Introduces weekly meal planning with a calendar-based tab view, per-recipe
date assignments synced via Nextcloud Cookbook custom metadata, and 30-day
automatic pruning of old entries on load, save, and sync merge.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Nextcloud Cookbook iOS Client/Views/Tabs/RecipeTabView.swift

@@ -13,6 +13,7 @@ import SwiftUI
 struct RecipeTabView: View {
     @EnvironmentObject var appState: AppState
     @EnvironmentObject var groceryList: GroceryListManager
+    @EnvironmentObject var mealPlan: MealPlanManager
     @EnvironmentObject var viewModel: RecipeTabView.ViewModel
     @Environment(\.horizontalSizeClass) private var horizontalSizeClass
 
@@ -114,6 +115,7 @@ struct RecipeTabView: View {
                         }())
                         .environmentObject(appState)
                         .environmentObject(groceryList)
+                        .environmentObject(mealPlan)
                         .onAppear {
                             viewModel.importedRecipeDetail = nil
                         }
@@ -126,6 +128,7 @@ struct RecipeTabView: View {
                         .id(category.id)
                         .environmentObject(appState)
                         .environmentObject(groceryList)
+                        .environmentObject(mealPlan)
                     case .allRecipes:
                         AllRecipesListView(
                             onCreateNew: { viewModel.navigateToNewRecipe() },
@@ -133,12 +136,14 @@ struct RecipeTabView: View {
                         )
                         .environmentObject(appState)
                         .environmentObject(groceryList)
+                        .environmentObject(mealPlan)
                     }
                 }
                 .navigationDestination(for: Recipe.self) { recipe in
                     RecipeView(viewModel: RecipeView.ViewModel(recipe: recipe))
                         .environmentObject(appState)
                         .environmentObject(groceryList)
+                        .environmentObject(mealPlan)
                 }
             }
         } detail: {